检索结果-南通市图书馆

A novel tuned heave plate system for heave motion suppression and energy harvesting on semi-submersible platforms

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2016年第6期59卷 897-912页

作者： liu kun OU Jin Ping School of Civil Engineering Harbin Institute of Technology Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Institute of Ocean Deep Water Engineering Dalian University of Technology

Deepwater offshore structures such as semi-submersible platforms suffer powerful ocean waves due to their location and site condition. The long distance away from the shore also brings many difficulties to energy supply for the platform operation. How to reduce the response of the platform and convert the wave energy into electrical power is a meaningful topic. In this paper, a tuned heave plate system(THP) is presented and designed to be employed on a semi-submersible platform for heave motion suppression and energy harvesting. This THP system is composed of spring supports, a power take-off system(PTO), and a heave plate. The PTO system is a permanent magnet linear generator(PMLG), which could directly convert the kinetic energy of the heave plate into electronic power. The stiffness of the spring supports is designed based on the principle of the tuned mass damper(TMD). The numerical model of the platform and the THP system is established according to the hydrodynamic analysis results of the platform. The model is tested and modified by scale model tests on the platform in the wave tank. A parameter study, including the size, tuned period, and damping ratio of the THP system, is conducted systematically based on the numerical model. The optimal parameters of the THP are selected due to the maximum heave motion reduction under severe wave conditions in South China Sea. The performance of the semi-submersible with and without the THP system under different wave conditions is analyzed. It is demonstrated that this novel tuned heave plate system could reduce the heave motion of the semi-submersible platform significantly and generate considerable power, which makes the THP system have a broad prospect for development.

关键词： heave motion semi-submersible wave energy harvesting wave energy converter TMD

Artemisinin, GABA signaling and cell reprogramming： when an old drug meets modern medicine

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2017年第6期62卷 386-387页

作者： Hai-kun liu Division of Molecular Neurogenetics German Cancer Research Center (DI(FZ) DKFZ-ZMBH Alliance Heidelberg 69120 Germany

The hormone-secreting endocrine cells(α,β,δ,ε and PP cells)form pancreatic islets,which are strongly involved in regulation of *** of insulin-producingβcells is the major cause of type 1 *** progress in cell reprogramming demonstrates the feasibility of generating functionalβcells to treat type 1 diabetes[1].However,a non-invasive in vivo approach forβcell reprogramming is still ***,two reports in

关键词： GABA cell Artemisinin,GABA signaling and cell reprogramming:when an old drug meets modern medicine

Effects of geometric configuration on droplet generation in Y-junctions and anti-Y-junctions microchannels

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2015年第5期31卷 741-749页

作者： Zhao-Miao liu Li-kun liu Feng Shen College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology

Droplets generation in Y-junctions and anti-Yjunctions microchannels are experimentally studied using a high speed digital microscopic system and numerical *** configuration of a microchannel,such as Y-angle（90°,135°,-90° and-135°）,channel depth and other factors have been taken into *** is found that droplets generated in anti-Y-junctions have a smaller size and a shorter generation cycle compared with those in Yjunctions under the same experimental *** observing the internal velocity field,the vortex appearing in continuous phase in anti-Y-junctions is one of the key factors for the difference of droplet size and generation *** is found that droplet size is bigger and generation cycle is longer when the absolute angle value of the intersection between the continuous and the dispersed phases（i.e.,the angle between the main channel and the continuous phase or the dispersed phase channel） *** droplet＇s size is influenced by the Y-angle,which varies with the channel depth in *** Y-angle has a positive effect on the droplet generation cycle,but a smaller height-width ratio will enhance the impact of a continuous and dispersed phase＇s intersection angle on the droplet generation cycle in Y-junctions microchannels.

关键词： Microfluidics Y-junctions and anti-Yjunctions microchannels Y-angle Height-width ratio in cross section

ABRUPT DEFLECTED SUPERCRITICAL WATER FLOW-REVISED THEORY OF SHOCK WAVE

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2006年第1期18卷 32-39页

作者： NI Han-gen liu Ya-kun State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China

The shock wave angle and depth ratio of the abrupt deflected supercritical water flow due to deflector was investigated experimentally and theoretically. A correction coefficient of the hydro-dynamic pressure ξ was introduced to generalize the momentum equation in the perpendicular direction to the shock front. An extensive series of tests were conducted in a 1 m wide flume with the Froude number ranging from 1.70 to 8.37, the deflection angle ranging from 5° to 40° and the length of deflector ranging from 0.28 m to 1 m. A dimensionless parameter K was defined to depict the ratio of the flow height to flow thickness. Test results show that the val ue of ~, the correction coefficient of the non-hydrostatic pres- sure distribution, decreases with the increase of the value of K An empirical relationship between the value of ξ and the val ue of K was proposed. It is indicated that the relative errors of the results calculated by the revised theory is much smaller than that obtained from the Ippen theory. Finally, a simple explicit expression was suggested to calculate the shock wave height ratio in consideration of the effect of the non-hydrostatic pressure distribution.

关键词： theory of shock wave abrupt deflection of supercritical flow trajectory type energy dissipater

MODIFIED LOG-WAKE LAWS FOR TURBULENT FLOW OF THE OUTER AND INNER REGIONS IN SMOOTH PIPES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第2期19卷 188-194页

作者： liu Ya-kun NI Han-gen State key Laboratory of Coastal and offshore Engineering Dalian University of Technology Dalian 116024 china

Based on theoretical analysis two modified log-wake laws for turbulent flow in smooth pipes are obtained, one is applicable to the outer region and other one to inner region, the new law for the outer region fits the velocity profile measured in smooth pipes by Zagarola very well and the effect of Reynolds number can be taken into consideration, the velocity profile for inner region satisfies the wall boundary conditions ,equals zero at the pipe wall and smoothly joins up with the velocity profile in outer region, the adopted eddy viscosity model is consistent with Laufer＇s, Nunner＇s and Reichardt＇s experimental data.

关键词： turbulent pipe flow eddy viscosity log-wakelaw outer and inner regions

General moving objects recognition method based on graph embedding dimension reduction algorithm

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第7期10卷 976-984页

作者： Yi ZHANG Jie YANG kun liu Institute of Image Processing and Pattern Recognition Shanghai Jiao Tong University Shanghai 200240 China

Effective and robust recognition and tracking of objects are the key problems in visual surveillance systems. Most existing object recognition methods were designed with particular objects in mind. This study presents a general moving objects recognition method using global features of targets. Targets are extracted with an adaptive Gaussian mixture model and their silhouette images are captured and unified. A new objects silhouette database is built to provide abundant samples to train the subspace feature. This database is more convincing than the previous ones. A more effective dimension reduction method based on graph embedding is used to obtain the projection eigenvector. In our experiments, we show the effective performance of our method in addressing the moving objects recognition problem and its superiority compared with the previous methods.

关键词： Moving objects recognition Adaptive Gaussian mixture model Principal component analysis Linear discriminant analysis Marginal Fisher analysis

Acoustic logging response law in shales based on petrophysical model

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第5期19卷 2120-2130页

作者： Song Hu Wei-Nan liu Ying-Ming liu kun liu Petroleum Exploration and Production Research Institute SINOPECBeijing100083China Shenzhen Branch of CNOOC(China)Co. Ltd.ShenzhenGuangdong518067China Research Institute of Petroleum Exploration and Development CNPCBeijing100083China

Shale acoustic logging response law is complex due to the multiple minerals and pores,which limits the application of acoustic logging in shale reservoir parameter evaluation,therefore clarifying the shale acoustic logging response law is of great *** petrophysical models are adopted for the equivalence of organic matter,clay,matrix minerals,and fractures,in Wufeng-Longmaxi shale formation in the Jiaoshiba ***,the self-consistent approximation model is used to combine different components,and a shale petrophysical model with a complex pore structure is *** model verification results show it has good predictability for *** on the model,the effect of different mineral compositions and different types of pores are *** results show that:1)The effect of clay and organic matter is very complex,and the variation laws of layered clay(organic matter)and dispersed clay(organic matter)on the acoustic wave are consistent.2)Layered clay or organic matter leads to the formation anisotropy increase,which makes the acoustic time difference greater than that of containing dispersed clay(organic matter).3)The fracture is the main control factor of anisotropy,and the anisotropy of gas-bearing fracture is higher than that of water/oil fracture.

关键词： Shale reservoir Acoustic logging Response law Complex pore structure Clay Fracture Organic matter

Prediction of network attack profit path based on NAPG model

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2020年第5期27卷 91-102页

作者： liu kun Wang Hui Shen Zihao College of Computer Science and Technology Henan Polytechnic UniversityJiaozuo 454000China

The network attack profit graph(NAPG)model and the attack profit path predication algorithm are presented herein to cover the shortage of considerations in attacker’s subjective factors based on existing network attack path prediction ***,the attack profit is introduced,with the attack profit matrix designed and the attack profit matrix generation algorithm given ***,a path profit feasibility analysis algorithm is proposed to analyze the network feasibility of realizing profit of attack ***,an opportunity profit path and an optimal profit path are introduced with the selection algorithm and the prediction algorithm designed for accurate prediction of the *** to the experimental test,the network attack profit path predication algorithm is applicable for accurate prediction of the opportunity profit path and the optimal profit path.

关键词： network attack graph technology attack profit profit matrix attack profit rate network path prediction

Contourlet transform for image fusion using cycle spinning

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2011年第2期22卷 353-357页

作者： kun liu Lei Guo Jingsong Chen School of Information Engineering Shanghai Maritime University Shanghai 200135 R R. China School of Automation Northwestern Polytechnical University Xi'an 710072 P. R. China China National Aeronautical Radio Electronics Research Institute Shanghai 200233 E R. China

A new method for image fusion based on Contourlet transform and cycle spinning is proposed. Contourlet transform is a flexible multiresolution, local and directional image expansion, also provids a sparse representation for two-dimensional piece-wise smooth signals resembling images. Due to lack of translation invariance property in Contourlet transform, the conventional image fusion algorithm based on Contourlet transform introduces many artifacts. According to the theory of cycle spinning applied to image denoising, an invariance transform can reduce the artifacts through a series of processing efficiently. So the technology of cycle spinning is introduced to develop the translation invariant Contourlet fusion algorithm. This method can effectively eliminate the Gibbs-like phenomenon, extract the characteristics of original images, and preserve more important information. Experimental results show the simplicity and effectiveness of the method and its advantages over the conventional approaches.

关键词： image processing image fusion Contourlet transform cycle spinning.